Recent studies have identified a novel population of blood-borne cells, termed fibrocytes, that have a distinct cell surface phenotype (CD34+/collagen +/CD13+/CD45+), and express each of the known surface components that are required for antigen presentation, including class I and class ll MHC molecules (HLA-DP, -DQ, and -DR), the co-stimulatory molecules CD80 and CD86, and the adhesion molecules CD11a, CD54, and CD58. Human fibrocytes induce antigen presenting cell (APC) -dependent T cell proliferation and this proliferative activity is as high as that induced by purified dendritic cells. In their present form, fibrocytes are significantly easier to isolate and culture than are dendritic cells. Importantly, mouse fibrocytes pulsed in vitro with the HIV-proteins p24 or gp 120 and delivered to a site of cutaneous injury migrate to proximal lymph nodes and specifically prime naive T cells. This project will Optimize growth and culture conditions for ex vivo human fibrocyte growth, antigen display, and induction of T-cell responses measured both in vitro and in vivo. It is expected that positive data from these studies will provide the basis for validated GLP methods required for initiation of clinical trials involving autologous fibrocytes for anti-cancer and ultimately anti-HIV therapies. PROPOSED COMMERCIAL APPLICATION: Fibroyctes have the potential for use as a vaccine in cancer and certain viral diseases.